Macrophages cultured with lymphocyte mediators are found to display a number of activated functions. These include increased ruffled membrane activity, increased pinocytosis and increased binding to tumor cells. The role of the surface membrane is prominent in many of the altered functions. The emphasis of the investigation will be the dissection of the components of the plasma membrane, especially the glycoproteins. To analyze plasma membrane glycoproteins we will use several sensitive techniques including radiolabeling of surface proteins, gel electrophoresis, autoradiography, and affinity chromatography. Our research will concentrate on the characterization and purification of serine proteinases, the major trypsin-sensitive cell surface component, a 160,000 dalton glycoprotein, and the C3b receptor of the macrophage, proteins whose functions are changed upon activation. Furthermore, comparison of the surface proteins of activated macrophages with those of nonactivated cells will help to correlate functional changes with alterations in particular proteins.